Disconnecting the battery is a real bad idea on a General Motors or Volkswagen vehicle. They have all kinds of things designed in to force you to go back to the dealer, usually on a tow truck, after doing that. Since the '87 models, the generators are a real poor design. They develop huge voltage spikes that interfere with sensor signals and they can confuse the various computers and cause them to lock up or perform the wrong functions. The battery is responsible for dampening and absorbing those spikes. As they age, they lose their ability to do that. Those spikes are also well-known to damage the internal diodes and voltage regulator in the generator. Repeat generator failures are common, but replacing the battery at the same time will reduce the number of those failures. The catch though is some computers lock up when the battery is disconnected to be replaced.
At four years old, it's about time for your battery to start losing its capacity. It may work fine yet in an '86 or older model, but you can justify replacing it now. Use a memory saver while the cables are disconnected. Some inexpensive ones plug into the cigarette lighter but the lighter must work with the ignition switch turned off for that product to work. I prefer to connect a small battery charger to the battery cables, but you must be careful that the clamps don't become disconnected while the battery is removed, and the positive cable can't touch anything metal on the car.
If the problem continues, you're pretty much stuck going to the dealer. All of the things you mentioned have the Body Computer in common, and in many models, to prevent you from replacing the high-failure radio with an aftermarket one, they built the Body Computer into it. If it needs to be replaced or repaired, only the dealer can reprogram it after it comes back from their grossly overpriced repair center.
Saturday, August 27th, 2011 AT 8:33 PM